This invention generally related to molding apparatus for use in conjunction with packaging machines of the kind in which the packages are formed of thermoplastic sheet material and, more particularly, to a packaging machine provided with an improved molding apparatus which allows the molding die to be readily removed.
The molding apparatus of this invention generally comprises a shaping tool having an upper portion secured on a machine frame and a reciprocating lower tool portion cooperating therewith. The thermoplastic sheet material is clamped between the two tool portions. A molding die is provided in the upper tool portion and may be receiprocated between a lower position extending into the lower portion and an upper position retracted therefrom. Drive to the molding die is provided by a piston cylinder device mounted ahead the cover of the upper portion, the piston rod extending through the top cover to be connected with the molding die or with a plate supporting the same. The lower portion is adapted to receive partitions and/or molding inserts in accordance with the shape and the dimensions of the package parts to be formed. The molding die is adapted to the respective molding inserts or partitions and may be formed of several individual die members each of which is secured on its top side to the plate reciprocated by the piston rod. When the dimensions of the molding members are to be changed, the upper portion and its outer casing with the piston cylinder device and the molding dies arranged in the upper portion have to be removed from the molding station. Subsequently and from the bottom side, the die members may be unscrewed from the plate connected with the piston rod, and thereafter the new molding dies may be screwed thereto. After removing the upper portion, the lower portion is accessible so that the molding inserts or partition members may be replaced.
However, a shaping tool of this type suffers from the drawback that it requires a relatively large overall height and that the operations required for changing the dimensions, i.e. replacement of the molding die and the molding inserts or partition members, are very complicated.
In a conventional hot molding machine for molding pieces of plastics material, the upper portion of the molding die is secured on a yoke member from the bottom side. Through a driven pinion, the latter is in engagement with rack members vertically mounted in a frame, to be reciprocated towards the lower part of the tool and away therefrom. For replacement of the upper part of the tool, the yoke member is sufficiently moved upwardly to have sufficient space between the upper and lower tool parts for manipulation on the upper tool part.